Machine for treating paper pulp stock to vary the consistency thereof



Oct. 3, 1961 w. F. MATHEWSON MACHINE FOR TREATING PAPER PULP STOCK TO VARY THE CONSISTENCY THEREOF Filed Feb. 4, 1958 10 Sheets-$heet 1 aria; QM

19.61 w. F. MATHEWSON 3,002,622

MACHINE FOR TREATING PAPER PULP STOCK TO VARY THE CONSISTENCY THEREOF Filed Feb. 4, 1958 10 Sheets-Sheet 2 1961 w. F. 'MATHEWSON 3,002,622

MACHINE FOR TREATING PAPER PULP STOCK To VARY THE CONSISTENCY THEREOF Filed Feb. 4, 1958 l0 Sheets-Sheet 4 /A/l/'/VTOQ a 8, A nrmm-y vOct- 1961 w. F. MATHEWSON 3,002,622

MACHINE F0 REATING PAPER PULP S K TO VARY E CONSISTENCY THEREO Filed Feb. 4, 1958 10 Sheets-Sheet 5 Arrow/5') Oct. 3, 1961 w. F. MATHEWSON MACHINE FOR TREATING PAPER PULP STOCK To VARY THE CONSISTENCY THEREOF l0 Sheets-Sheet 6 Filed Feb. 4, 1958 Oct. 3, 1961 w. F. MATHEWSON 3,002,622

MACHINE FOR TREATING PAPER PULP STOCK To VARY THE CONSISTENCY THEREOF Filed Feb. 4, 1958 10 Sheets-Sheet 7 mwcM ATTORNEY Oct. 3, 1961 w. F. MATHEWSON MACHINE FOR TREATING PAPER PULP STOCK TO VARY THE CONSISTENCY THEREOF l0 Sheets-Sheet 8 Filed Feb. 4, 1958 Oct. 3, 1961 w. F. MATHEWSON MACHINE FOR TREATING PAPER PULP STOCK TO VARY THE CONSISTENCY THEREOF l0 Sheets-Sheet 9 Filed Feb. 4, 1958 1961 w. F. MATHEWSON 3,002,622

MACHINE FOR TREATING PAPER PULP STOCK To VARY THE CONSISTENCY THEREOF Filed Feb. 4, 1958 10 Sheets-Sheet 1o ATTORNEY 3,002,622 MACHINE FOR ATENG PAPER PULP STOCK T VARY TIE CONSISTEN CY THEREOF Wilfred F. Mathewson, 261 Franklin St, Weymouth 10, Mass. Filed Feb. 4, 1958, Ser. No. 713,136 9 Claims. Cl. 209-250 This invention relates to a machine for heating pulp stock such as is used in making paper, and it has for one of its objects to provide an apparatus which can be used either as a pulp screen for screening raw pulp stock to separate the acceptable portion thereof from the unacceptable portion, which latter is sometimes referred to as the tailings, and to deliver the acceptable and unacceptable portions into different receivers, or can be used as a filter for pulp stock to, strain or filter out from the stock a portion of the water content thereof in order to thicken said stock.

The device herein shown is of that type which includes a cylindrical screen element mounted to rotate about a horizontal axis, and another object of the invention is to provide such a machine in which the cylindrical screen element is mounted on and supported by a tubular shaft into which the stock to be treated is delivered and from which such stock is delivered on to the interior face of the screen in the form of a sheet of stock which extends from one end of the screen to the other.

The screening wall of the screen element herein shown is in the form of a helix of flat wire which has been bent edgewise to produce said helix, and another object of the invention is to provide a novel screening wall of this type which has a smooth exterior surface free from any projections or protuberances.

Still another object of the invention is to provide a novel means for applying the force for rotating the screen element to both ends thereof thereby preventing said screen element from becoming twisted or distorted by having the rotative force or torque applied to one end only.

Other objects of the invention are to improve generally machines of this type as will be more fully set forth in the following description.

In the construction illustrated the apparatus is set up to function as a screen for screening raw pulp stock, but by changing the character of the screen element the appar-atus may be used as a pulp thickener, as will be later described.

In the drawings:

FIG. 1 shows one end of an apparatus embodying my invention,

FIG. 2 is a view of the other end of the apparatus,

FIG. 3 is a section on the line 3--3 FIG. 2,

FIG. 4 is a section on the line 4-4 FIG. 3,

FIG. 5 is a section on the line 55 FIG. 3,

FIG. 6 is a section on the line 6-6 FIG. 3,

FIG. 7 is a fragmentary view showing one of the end members of the screening element with a part broken out,

FIG. 8 is a section on the line 88 FIG. 9,

FIG. 9 is an enlarged sectional view taken on the line 33 FIG. 2, but showing only the left hand end of what is shown in FIG. 3,

FIG. 10 is a sectional view, with parts broken out, of the shower pipe,

FIG. 11 is a fragmentary view of the shower pipe showing the slotted flat face thereof,

FIG. 12 is an enlarged sectional view of the shower p p FIG. 13 is an end View of the screening wall of the screen element showing the notches cut in the turns of the helix to receive the supporting bars,

FIG. 14 is a section taken on the line 14-44 FIG. 15,

FIG. 15 is a plan view of FIG. 14,

FIG. 16 is a fragmentary sectional view of one end of the screening wall,

FIG. 17 is a fragmentary perspective view showing the interlocking connection between the turns of the helix and the supporting bars,

FIG. 18 is a perspective view illustration, a portion of the helical screening wall,

FIG. 19 is a view of the collar 65, and,

FIG. 20 is a section on the line 20-20 FIG. 19.

The apparatus illustrated herein comprises a casing 3 in which is located a rotary screen element. 4 having a cylindrical screening wall 5, the construction of which will be described later, said screen element rotating about a. horizontal axis.

The casing 3 is made with two end members 7 and 8 and a body which encloses the screen element 4 and comprises a bottom section 9 and a top section 10. The bottom section 9 is provided with a flange 11 which engages the inside wall of the end member 7 and is secured thereto by bolts or screws 13. The end member 8 presents a body portion 15 and an upper window portion which includes a circular Window 17 of some transparent material that is mounted in a circular frame 18, the latter having an interior rabbet 18a to receive the edge of the window 17. The upper edge of the body portion 15 is concavely curved to correspond to the lower convexly curved half of the frame 18, said curved edge of the body 15 and the rabbet 18a in the frame 18 forming between them a groove to receive the edge of the window 17. The frame 18 is secured to the body member 15 by means of screws 19. The upper edge of the frame 18 is enclosed by the edge of the top section 10 of the casing and said edges may be secured together by any suitable means. The circular frame 18 has. a plurality of inwardly directed radial arms 20 which are rigid with a hub member 21 in which is rotatably mounted one end of a shaft 24 on which the rotary screen element 4 is mounted, said hub having suitable bearings 22 for the shaft. The said shaft is driven by a driving pulley 25 which is fast thereon.

The shaft 24 has a solid end portion 24:: which extends through and is supported by the hub 21 and an enlarged tubular portion 26 which extends from one end of the screen element 4 to and through the other end and into the end member 7 .of the casing, said end member 7 having a bearing 23 in which the end of the tubular portion 26 of the shaft is supported. Said shaft is open at its end as indicated at 27, and said open end registers with an inlet opening 28 with which the end member 7 of the casing is provided.

The screening element 4 is in some respects similar to that illustrated in my co-pending application Ser. No. 636,807, filed January 28, 1957, in that the screening wall 5 is formed of a flat wire which is bent edgewise into the form of a cylindrical helix or coil, the adjacent turns of the helix being spaced from each other by a distance to provide screening slots of the desired width. The cylindrical screening wall is mounted on two screen end members 54 and 54a, both of which are rigidly mounted on the shaft 24, the end member 54a being secured to the solid portion 24a of said shaft and the other end member 54 being secured to the end of the tubular section 26 of said shaft.

The screen end member 54a is in the form of a spider which has a hub that is mounted on and secured to the solid portion 24a of the shaft 24, and radiating arms 81 which support a rim 82 on which one end of the screening wall 5 is mounted.

The other screen end member 54 has a general cup 3 shape and is provided with an opening in its bottom wall 56 through which the end of tubular portion 26 of the shaft 24 extends, said bottom wall being secured by screws 55 to a flange. 55w extending from said tubular portion. The open end of the screen end member 54 has a rim portion 83 on which the other end of the screening wall 5 is mounted.

As stated above, the screening, wall 5 is formed of a fiat wire 84 bent edgewise into the form of a cylindrical helix 85, a portion of which is illustrated in FIG. 18,

although the proportions. depicted. in said figure are not realistic. Such a coil or helix provides between its turns a spiral slot 86 which extends from one end to the other thereof.

The helix 85 is mounted on a plurality of supporting bars 87 which extend from one end to the other of the screening wall and are all parallel with the axis about which the screen element revolves. Each bar is mounted in notches 88' cut in the outer portions of the turns 84a of the coil. The bars 87 and the notches 88 have such proportions that the outer faces of the bars are flush with the outer faces of the turns 84a. This provides a screening wall that has a smooth outer face that is free from any projections.

The bars 87 are provided with means to hold the turns 84w properly spaced from each other to provide a screening slot 86 of the proper width. One or both of two opposite sides of each bar 87 is provided with positioning ribs 39 which provide between them grooves 90, each having a width equal to the thickness of the fiat wire 84. The edge 90a of each turn of the helix, which constitutes the edge of a notch 83 therein, fits into a groove 90 as shown in FIGS. and 17, and the turns 84a are thus all held firmly in proper spaced relation.

The ends 91 of the bars 87 are reduced in size and are circular in cross-section and project beyond the ends of the coil 85, and through supporting rings M, in which they are anchored by means of nuts threaded on the ends thereof Each supporting ring 92 is detaohably secured to the rim of its screen end member by a split snap spring ring 93 which occupies a groove 94 in the inner face of said supporting ring 92 and engages a shoulder 95 on the rim 82 of the screen end member to which it is attached. The ends $6 of the split snap ring 9 3 are bent outwardly as shown in FIG. 8 and occupy 'a recess 97 in the side of the supporting ring 92 of the screening wall 5. The snap ring 93 can be placed in or removed from its operative position by grasping the ends 96 and moving them towards each other thereby contracting the diameter of the split ring sufficiently for this purpose.

The portion of the tubular part 26 of the shaft that lies within the rotary screen element 4 has openings 29 therethrough and is enclosed in a tubular stationary core member 31 which provides a receiving chamber 34 with which the openings 29 in the tubular shaft communicate. The stationary core member 31 is supported on the shaft 24, said core member having a hub portion 32 through which the solid portion 24a of the shaft 24 extends, a roller or other anti-friction bearing 33 carried by said stationary hub portion 32 serves to reduce friction between said hub portion and the shaft. At the other end of the core member there is provided an antifriction hearing. 61 between the tubular portion 26 of the rotatable shaft and the stationary core member 31. The shaft 24 is thus supported at one end in the bearing 22 and at the other end in the bearings 23, and the stationary core member is supported by the shaft through the bearings 33 and 61. The means by which the core member 31 is held stationary while the shaft 24 is rotating will be presently described.

Raw pulp stock which is delivered to the inlet opening 28 flows into the open end 27 of the tubular portion 26 of the shaft 24, thence through the openings 29 into the receiving chamber 34, from which it is delivered onto the inner face of the screening wall 5 by means now to be described. The core member 31 is provided with a delivery nozzle 35 (see FIG. 4) which has an elongated downwardly directed delivery slot 36 that extends the length of the screen element 4 and is situated parallel with the screening wall 5 and closely adjacent thereto but spaced slightly therefrom. The raw stock in the receiving chamber 34 is thus delivered through the slot 36 in the form of a sheet which is directed downwardly against the inner face of the screening wall 5 and in the same direction as that in which the wall is moving as shown by the arrow 37 in FIG. 4. The portion of the stock which passes through the screening wall 5 drops into the lower portion of the bottom section 9 of the casing and collects in the chamber 38 which has an open end that registers with the discharge opening 39 of the end member 7.

The portion of the stock which does not pass through the screening wall 5 remains on the inner face thereof and is carried forward thereby until it is dislodged therefrom by a spray from a shower pipe 45 located on the outside of the screening wall but closely adjacent thereto. The material thus dislodged drops onto an inclined apron 41? carried by the stationary core member 31, from which it gravitates into a chamber 42 at the lower end of the apron. The material accumulating in the chamber 42 is delivered through openings 75 in the screen end member 54 into a chamber 43 in the end member 7 of the casing and which is provided with a discharge opening 44 through which such material is delivered. If the device is being used for screening pulp stock, the portion of the raw stock which passes through the screening wall 5 and is delivered through the discharge opening 39 will be the acceptable portion of the unscreened stock, and the portion of the raw stock which does not pass through the screening wa l 5 will be the so-called tailings and will be delivered through the discharge opening 44.

The shower pipe 45 extends the full length of the screen member 4 and has a flat side 46 which lies closely adjacent to the outside face of the screening wall 5. The exterior surface of said wall is free from projections so that said face 46 of the shower pipe may be separated from screening wall by a space only sufiicient to provide for proper clearance.

The flat face 46 of the shower pipe 45 extends the full length of the screen element 4, and it is provided with one or more openings through which water, compressed air or some other suitable fluid under pressure may be delivered onto the outer face of the screening wall 5 as the screen element rotates, thereby to dislodge or flush from the inner face of the screening wall any unscreened material that adheres thereto, such material being deposited on the apron and collecting in the chamber 42, from which it is discharged through the discharge opening 44 in the end member 7.

In the construction shown the opening in the face 46 is in the form of a slot 47 that extends from one end to the other of the screen.

The top section 10 of the casing 3 is divided into two parts 10a and 10b and the shower pipe 45 is located between said parts and is covered by a cover member 48 which is bolted to flanges 49 on the edges of the two parts Na and 10b by bolts 50. Water or air under pressure may be delivered to the inlet end 45a of the shower pipe by means of any suitable pipe connection.

As stated above, the core member 31, which carries the nozzle 35, is supported on the shaft 24 and is held from rotation and thus maintained in a stationary position. This is accomplished by means of two gear elements, one of which is rigidly held in a stationary position and the other of which is rigidly secured to the core member, together with one or more planetary gears, each of which meshes with both of the gear elements and is carried by the shaft and is mounted thereon for rotation about an axis other than that of the shaft and thus has an orbital movement about the shaft as it rotates.

The two gear elements above referred to are shown at 69 and 73 respectively. The gear element 69 is shown as cup-shaped and is rigidly secured to the end member 7 of the casing 3, as shown at 79. Said gear element is provided with internal gear teeth 68 which encircle the outer end of the screen end member 54. The gear element 73 is in the form of a gear ring and is secured to the end 60 of the core member 31 by means of bolts or screws 74, said gear 73 having internal gear teeth 72.

In the embodiment shown there are three planetary gears which cooperate with the said gear element, one of which is shown at 62 in FIGS. 3 and 9.

Each planetary gear 62 is in the form of a duplex gear and has two sets of gear teeth 67 and 71 (see FIG. 9), the teeth 67 meshing with the teeth 68 of the stationary gear element 69 and the teeth 71 meshing with the teeth 72 of the gear element 73.

The planetary gears 62 are mounted as follows: The end wall 56 of the screen end member 54 is provided with three recesses 57 spaced 120 apart, each adapted to receive a roller bearing 58 in which is mounted the hub 59 of one of the planetary duplex gears 62. The other end of said planetary duplex gear has a hub 63 mounted in roller bearings 64 in a recess 66a in an extension 66 formed on a collar 65 (see FIG. 19) that encircles the tubular portion 26 of the shaft 24 and is secured thereto by bolts 65a. As stated above, in the embodiment shown there are three of the planetary duplex gears 62, each of which is carried bodily by the tubular portion 26 of shaft 24 and thus has an orbital movement about said shaft. In the construction shown each planetary gear is so mounted that its axis of rotation is parallel to that of the shaft 24. The two internal gear elements 69 and 73 are the same size and have the same number of teeth, and the two toothed portions 67 and 71 of each planetary gear 62 are also the same size and have the same number of teeth. The end 60 of the core member 31 is spaced from the open end of the cup shaped gear member 69, and the screen end member 54 has an intermediate curved portion 7 8 which extends through said space so that the end of the screen end member 54 which is secured to the screen element 4 is located outside of the core member 31 and the other end 56 of said end member 54 is located inside of the gear member 69.

With this construction the orbital movement of the planetary duplex gears 62 will cause the tooth sections 67 and 71 of each gear to roll over the teeth 68 and 72 of the stationary interior gear elements 69 and 73, and since said duplex gears are maintained with their axes parallel with that of the shaft, not only will the end 66 of the core member 31 be held firmly in its correct stationary position, but the rotative force of the tubular portion 26 of the shaft 24 will be delivered to the screen end member 54 and thereby rotative force will be applied to the screen element at both ends. An advantage of this is that said screen is not subjected to force tending to twist it as might be the case if the entire force for rotating it were applied at one end only.

Although I have shown a construction in which the planetary gears 62 rotate about axes that are parallel with the axis of the shaft 24, yet I regard a construction in which the planetary gears each rotate about an axis which is not parallel with shaft axis as coming Within my invention.

The screening wall is shown as being slightly bowed, it having a slightly larger diameter at its central portion than at its ends, whereby the rigidity of the screen is increased.

While 'I have described above and shown in the drawings the apparatus as it might be used for screening pulp stock and as having a screening wall 5 that contains the exact requirements of a fractionating screen which passes the acceptable fibre, yet it is within the scope of the invention to use the structure as a filter for the purpose of thickening screened stock. This would involve merely substituting for the particular screening wall shown, any commercially available screening element which is adapted for a rotary screen and has the proper construction to function as a filter.

For example, the screening wall of the rotary screen element 4 might be in the form of a metal mesh filter cloth attached directly to the supporting rings 92 by means of the split snap rings 93.

When used as a thickener the screened stock to be thickened will be delivered to the inlet opening 2 8 and to the interior of the tubular portion 26 of the shaft 24, and such stock will pass through the openings 29 of said tubular shaft portion 26 into the collecting chamber 34 and will then be delivered onto the inner face of the screening wall through the nozzle slot 36.

Because of the construction of the screening wall which is used for this purpose the fibre content of the stock will be retained on the inner face of said screening wall, but some of the water content will drain through the filter wall and will collect in the chamber 38, and will be discharged through the discharge opening 39. The passage of the surplus water through the screening wall will be augmented by the centrifugal force developed by the rotation of the screen element.

The stock which is retained on the inner face of the screening wall will be dislodged therefrom by a sheet of compressed air or other fluid delivered through the slot 47 of the pipe 45, and will gravitate downwardly onto the apron 40 and collect in the chamber 42. From the chamber 42 the thickened stock will flow through the openings 75 in the end member 54 of the screen element and through the passage 43 to and through the discharge opening 44. i

I claim:

1. A machine for treating pulp stock comprising a rotary cylindrical screen element having a cylindrical screening wall, a horizontal tubular shaft extending axially through the screen element, means to rotate said shaft, means mounting the screen element on the shaft to rotate therewith, means to deliver the pulp stock to be treated to the interior of said rotatable tubular shaft, the latter having openings through the wall thereof through which the pulp stock is delivered therefrom, and means including a stationary nozzle element situated within the screen element and provided with a delivery slot extending parallel to the axis of the shaft to deliver the pulp stock on to the inner face of the screening wall in the form of a sheet.

2. In a machine for treating pulp stock, a rotary cylindrical screen element having a cylindrical screening wall, a horizontal tubular shaft extending axially through the screen element, means to rotate the shaft, means rigidly mounting said screen element on said shaft to rotate therewith, means to deliver the pulp stock to be treated to the interior of said rotary tubular shaft, the latter having openings through which said stock is delivered from the shaft, a stationary receiving chamber within the screen member and through which the tubular shaft extends, said receiving chamber being situated to receive the stock delivered through the openings in said shaft, means supporting the receiving chamber on the tubular shaft, means to hold said receiving chamber from rotative movement, said stationary receiving chamber having a nozzle portion provided with a delivery slot extending parallel to the axis of the shaft and situated to deliver the stock to be treated on to the inner face of the screening wall in the form of a sheet.

3. A machine for treating pulp stock comprising a rotary cylindrical screen member having a cylindrical screening wall, a horizontal tubular shaft extending axially through the screen member and to which the latter is rigidly attached, means to rotate the shaft about its axis, means to deliver pulp stock to be treated to the interior of said tubular shaft, the latter having openings through which said pulp stock is delivered therefrom, a stationary core member within the screen member, means supportingthe core member on said tubular shaft, means to hold said core member from rotative movement, said core member having a receiving chamber to receive the pulp stock as it is discharged through the openings in the tubular shaft and also having a nozzle portion provided with a delivery slot extending parallel to the axis of the tubular shaft and the length of the screen member, said slot being situated to deliver the pulp stock from the receiving chamber on to the inner face of the screening Wall in the form of a sheet.

4. A machine for treating pulp stock comprising a casing having two end members and a body member, a tubular shaft extending from one end member to the other, hearings in each end member in which said shaft is mounted for rotation, said tubular shaft having openings through the wall thereof, a cylindrical screen element mounted on said shaft for rotation therewith, said screen element having a cylindrical peripheral screening wall, means to rotate said shaft and screening element, one of said members having an intake opening therethrough which communicates with the interior of the tubular shaft and through which the pulp stock to be treated is delivered into said shaft, a stationary receiving chamber within the screen member situated to receive the pulp stock discharged from the tubular shaft through the openings therein, said receiving chamber encircling the tubular shaft means supporting said receiving chamber on said tubular shaft, means holding said receiving chamber from rotative movement, said receiving chamber having a nozzle portion provided with an elongated delivery slot situated adjacent to the inner face of the screening wall and extending from one end to the other of the screen element whereby the stock in the receiving chamber is discharged therefrom through said slot on to the inner face of the screening wall in the form of a sheet.

5. In a machine for treating pulp stock, a casing, a horizontal screen-supporting shaft mounted therein, means to rotate said shaft, a horizontal screen element mounted on said shaft to rotate therewith said screen element having a cylindrical screening wall, a stationary core member within the screen element, means supporting said core member on said shaft, means to hold said core member from rotative movement, said core member having a receiving chamber through which the shaft extends and also having a delivery nozzle communicating with said receiving chamber and adapted to deliver untreated stock from said chamber onto the inner face of the screening wall, means to deliver untreated stock into said receiving chamber and thence to the nozzle, and means to hold the core member from rotation.

6. In a machine for treating pulp stock, a casing, a horizontal screen-supporting shaft mounted therein, a horizontal screen element mounted on said shaft and having a cylindrical screening wall, a stationary core member within the screen element and encircling the shaft, means supporting said core member on said shaft, said core member having a receiving chamber and a delivery nozzle communicating therewith and adapted to deliver untreated stock from said chamber onto the inner face of the screening wall, means to rotate the shaft, means to deliver untreated stock into said receiving chamber and thence to the nozzle, and means to hold the core member from rotation, said last named means comprising two gear elements, means securing one gear element to a stationary support, means securing the other gear element to the core member, and a planetary gear carried by said shaft and mounted thereon to rotate about an axis other than that of the shaft, said planetary gear having operative engagement with both of the said gear elements.

7. In a machine for treating pulp stock, a casing, a horizontal screen-supporting shaft mounted therein, a horizontal screen element mounted on said shaft and having a cylindrical screening wall, a stationary core member within the screen element and encircling the shaft, means supporting the core member on the shaft, said core member having a receiving chamber and a delivery nozzle communicating therewith and adapted to deliver untreated stock from said chamber onto the inner face of the screening wall, means to rotate the shaft, means to deliver untreated stock into said receiving chamber and thence to the nozzle, and means to hold the core member from rotation, said last named means including two ring gear elements which encircle the shaft and are concentric therewith,'each gear element having internal gear teeth, means holding one gear element in a stationary position, means securing the other gear element rigidly to the core member and in a position concentric with the shaft, a planetary gear carried by the shaft and mounted thereon to rotate about an axis other than that of the shaft, said planetary gear having an orbital movement about the shaft as the latter rotates and also having two sets of gear teeth, the teeth of one set meshing with the gear teeth of one ring gear element and the teeth of the other set meshing with the teeth of the other ring gear element.

8. In a machine for treating pulp stock, a casing, a horizontal rotary screen-supporting shaft mounted therein, means to rotate said shaft, a horizontal cylindrical screen element presenting two end members mounted on said shaft and secured thereto and a cylindrical screening Wall carried by said end members, one of said end members having a cup shape, a stationary core member within the cylindrical screening element, said core member encircling the shaft, means supporting the core member on the shaft, one end of the core member being located within said cupshaped end member of the screening element and having rigid therewith an internal gear which encircles the shaft, a secondary stationary internal gear rigid with the casing, a planetary toothed gear member mounted on the exterior of said shaft to have a rotary movement about its own axis which is parallel to but spaced from that of said shaft and also to have an orbital movement about the shaft as the latter rotates, said gear member having on its exterior two sets of gear teeth, the teeth of one set meshing with the stationary internal gear which is secured to the casing and the teeth of the other set meshing with the teeth of the internal gear that is secured to one end of the core member, whereby the planetary gear during its orbital movement cooperates with the two stationary internal gears to hold the core member in its stationary position.

9. In a machine for treating pulp, a casing, a horizontal screen-supporting shaft mounted therein, a horizontal cylindrical screen element having two end members mounted on said shaft, one at each end thereof and a screening wall carried by said end members, means rigidly securing each end member to said shaft, one of said end members having a cup shape, a stationary core member within the cylindrical screen element, said core member encircling the shaft, means supporting the core member on the shaft, means holding the core member from rotation, one end of the core member being located within said cup-shaped end member of the screen element and having rigid therewith an internal gear which encircles the shaft, a second stationary internal gear rigid with the casing, a planetary toothed gear member mounted on the exterior of said shaft to have a rotary movement about its own axis which is parallel to but spaced from that of said shaft and also to have an orbital movement about the shaft as the latter rotates, said gear member having on its'exterior two sets of gear teeth, the teeth of one set meshing with the stationary internal gear which is secured to the casing and the teeth of the other set meshing with the teeth of the internal gear that is secured to one end of the stationary core member, means to rotate the shaft by applying torque to the end thereof opposite to that on which the cupshaped end member of the screen element is mounted, whereby during the orbital movement of the planetary gear produced by the rotation of said shaft said gear cooperates with the two stationary internal gears to maintain the core member in its stationary position and also to apply torque to the end of the shaft on which the planetary gear is mounted.

References Cited in the file of this patent UNITED STATES PATENTS 65,716 Alexander June 11, 1867 892,825 Gross July 7, 1908 10 1,451,522 Baxter Apr. 10, 1923 1,717,604 Hang et a1. June 18, 1929 1,843,791 Stadler Feb. 2, 1932 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No." 3,002,622 October 3 1961 Wilfred F. Mathewson I It is hereby certified that error appears in the above numbered pat-i entrequiring correction and that the said Letters Patent should read as "corrected below. H .v i

In the heading to the printed specification lines 4 and 5 for "Wilfred F. Mathewson 261 Franklin St., W Weymouth l0 1 Ell-ass B read Wilfred F. Mathewson Weymouth Mass (261 Franklin St, Boston 10, Mass,) column Ti line 243 after "said" insert end column 8 line .35 for "secondary 3 read second "a Signed and sealed this 3rd day of April 1962.,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD 1 I Attesting Officer Commissioner of Patel 

